Monty Cosby1,Nutifafa Doumon2,Amy Louks2,3,Minh Nguyen4,Michael Irwin4,Joseph J. Berry2,Laura Schelhas2,Kevin Stone1
Stanford Synchrotron Radiation Lightsource1,National Renewable Energy Laboratory2,Colorado School of Mines3,CubicPV4
Monty Cosby1,Nutifafa Doumon2,Amy Louks2,3,Minh Nguyen4,Michael Irwin4,Joseph J. Berry2,Laura Schelhas2,Kevin Stone1
Stanford Synchrotron Radiation Lightsource1,National Renewable Energy Laboratory2,Colorado School of Mines3,CubicPV4
Formamadinium lead idodide, FAPbI<sub>3</sub>, is at the forefront of metal halide perovskite (ABX<sub>3</sub>) research boasting an impressive 25% efficiency (as of this writing). The structural makeup of an FAPbI<sub>3</sub> thin film has been presumed to be primarily the FAPbI<sub>3</sub> cubic structure with potentially a low percentage of PbI<sub>2</sub>. Using comprehensive powder and grazing incidence diffraction methods, we have characterized these perovskite thin films in great detail to determine the subtle structural parameters which play a role in the material performance. Performance differences in the literature are typically ascribed to changes in processing conditions while the level of characterization is insufficient to determine if there are accompanying structural changes. Our work seeks to address this open question as to whether there are structural differences which correlate to the observed differences in material performance.